Estudos teoricos de solvatação ionica usando simulação computacional de Monte Carlo

AUTOR(ES)
DATA DE PUBLICAÇÃO

1995

RESUMO

The Monte Carlo method with Metropolis algorithm was used to study chloride solvation in water, methanol and water-methanol mixtures. The calculations were performed in the NVT and NpT ensembles at 298 K and 1 atm. These systems were modeled by cubic box containing one ion plus 400 or 200 solvents molecules with periodic boundary conditions. Lennard-Jones and Coulomb potentials were used to calculate intermolecular interactions. Interactions between solvent molecules were calculated using potential functions from literature and the parameters for methanol-chloride potential functions were developed in this work. These parameters were obtained by fitting ion-solvent interaction energy calculated by ab initio method. The MC311-G** base set was used and correlation energy included at the MP2 level. For each solvent, the free energy of solvation was calculated using thermodynamic perturbation theory. Results obtained for free energies of solvation are in good agreement with experimentals data. The structural analysis of solute-solvent interaction showed an average of four methanol molecules in the first solvation shell of chloride in pure methanol. For water-methanol binary mixtures the coordination number is not exactly defined in the first coordination shell. This fact is explained by the similar interaction between chloride-water and chloride-methanol in the gas phase revelead by ab initio calculations.

ASSUNTO(S)

solvação simulação (computadores) metodo de monte carlo solução ionica metodos de simulação

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